Gunfire control computer



y w. H. NEWELL I 2,403,544

GUNFIRE CONTROL COMPUTER Filed Feb. 21, 1941 2 Sheets-Sheet l lgx 92 N v a:

f F m I in N 4 m 2 S 4) 1946- w. H. NEWELL GUNFIRE CONTROL COMPUTER.

Filed Feb. 21, 1941 Z-Sheets-Sheet 2 SGLOOOI INVENTOR i Wi v. ATTORNEY Patented July 9, 1946 UNITED STATES m cUNFiRE CONTROL COMPUTER:

William Newell, New York, N. Y., assignor to Company, Inc., Long Island Ford Instrumentv City, N. Y., aco'rporationpf New York Application February 21, 1941,1Serial No. 379,926

This invention relates to gun-nre control com.- puters and particularly to that type oicomputers, used to control the firing of guns against aircraft.

The problem of the control of gun-fire against aircraft may be divided into two classes; (1) where the aircraft or target is approaching directly towards its objective or thepoint of'observation and the firing gun, target is passing at a distance to one ,sideor the. other of the observing and firing point. The invention herein disclosed is applied to the first mentioned class. It will of course be understood that $91118 f the principles thereof are applicable to the solution of problems of the second mentioned class. H V

In. considering the solution of the problem of; anti-aircraft fire control to-Which this invention is applied as one embodiment thereof, it is assumed that the target is: directly approaching its objective, which is the point of observation and the point of firin 0f the gun, at a substantially constant height above the horizontal plane of the objective, such as would be done in horizontal-bombing of a selected point. Upon the picking up of the target by observers at the objective, the slant range of the target and its elevation above the horizontal, expressed in angular units, are observed by instruments well known in the art and from the observed data the height of the target and the horizontal range may bedetermined, or if the height of the target is known or obtained by observations and the elevation is observed, the slant range and. the horizontal range may be determined.

From experimental data obtained during tar get practices, the most effective ranges of the guns are known as Well as the time in seconds required to set and adjust the sights andth fuses of the projectiles and to load and fire the projectiles. In this specification, the time required.

and (2) Where the to set the observed valuesinto the mechanisms for the mechanisms to calculate the advance range or fuse setting and the sight angle, and the time required to adjust the sight and gtm and load and fire the gun is defined as the preparation period of time. This preparation period is arbitrarily selected and is based upon experience under various circumstances of operation.

An object of the invention is to provide a mechanism settable in accordance with the speed of the target and including a vector analyzerv settable in accordance with the range or height and elevation angle of a moving aircraft target at the observing instant.

It is a further object of the invention to, provide a scale Or chart, associated with the target speed settin means, to aid the operator in selecting one of a plurality of predetermineddistances that the target will move during the necessary prepa: ration period of time and to provide aiplurality of indicators on the horizontal. range component of; .line thus defining the pointgB- atv Mechanisms-for aecompn'shm the objects Q'f the invention-and their operation will be un'de'rstoodby" considering the followingjdescription and accompanying drawings in which: f

Fig. 1 is an elevation-sideWiew of an aircraft tar et directly a prqachi anio s r i sa s in mint: at atonstant .heish i nd h w e: s ut v ra gu arran l n r a g s of t e ttq h ob erv neand e pint;

h fire i the rim; and

F g-.3 issan en ra dv dial of Fig. 2. i 3 Referring particularly to Big. 1, an air a or target I is directly approaching the observing and fir ng-point .0 at aconstantheight; (Ii). above-the horizontal O .0:an3d at. a r zontalsneed Qffit.

When the target I reaches ppint Arobse lers at O observe the; slant range JR), and theflelevatiOn .;an 1e:'.0f.,the:- target: .(A )g,..ri. om w ch. the height .;(H) and the horizontal, range (BI-l2 may be calculated by:

the qu tions. re ulting; from, the right angle triangle 0AA" RH =.R.i co s A- e t v hc. is. the; WWW: tion of,the-'p'oint A on the horiziontalO.0 N

The distance traveled by theitargetduringthe, necessary preparation period; of. time (XL is lselected as requiredandis represented by the length, h 9h the target I willbe atthe end ofithe preparation; period.- The value ;0fjthe distance AB maygbeiexpressed by the equation W t i t '1 X-St' j 41) Thefhorizontal range oi target l at point B IRE-133i" is equaltq-bhe observed horizontalv range minus h dista eAB r- ;r; :i a I RH3=RH+X stj 5- I From; the right. angle mmense. time vation of the target when; at; point B (A3) -will=be= the angle whosetangent'is the height. divided; by the horizontal range? to the point "B, or; g

.From'; ballistic tables or curves obtained, ,from' 1 experimental data the: time,0f;.fli'ght5.(t) of;pro.-. jectiles is ,iknqwn for various. combinationsof her-1 izontal ranges and heights. As is well known the time of flight travel of the target during this period of time is, equal to the speed of the target multiplied by the time of flight or t-St, and is indicated, on l by the line BC, or

This distance determines the point of intercept (C) and a perpendicular dropped-from C deter-. mines the point C. It is obvious that Q represents the horizontal range to the point of intercept (EH2), and that The elevation angle of the point of intercept (A2) is obtained from the right angle triangle OCC and is the, angle whose tangent is the. height divided by the horizontal range to the point ofintercept (RI-I2) or The elevation of the gun above the line of sight the point B, to allow for the movement of the target during the time of flight is known as veric jt an ula de e i n (U1?) and a e expressed as Referring particularly to Fig. 2, the vector analyzer 2 consists of a vector disk 3 and two componentslides L and. 5.

The disk 3 has a radial rangescale B engraved thereon. The range scale 6 terminates in an indeg-1 cooperating with an angular scale 8 fixedly mounted on the frame (not shown): of the in strument to indicate the angular position ofthe disk 3; The vector disk 3 is angularly positioned by the handle 9- connected to the disk shaftfll and gears H.

The component slide 4 isrestrainedby guides.

(notshown) to-movevertically, thatis at right angles to the plane of the constructive horizontal diameter. oi the disk I2 extending across thesaid constructive horizontal diameter. represents height (H)- of. the target and its position relative to the center of the disk 3 is indicated by the height scale l3 read against The slide 4 and-the wirel2 are located in accordance with theheight of the endof the wire l2;

the target by the handle L4 acting through the shafting l and the gears IS.

The component slide- 5' is restrained by guides (not shown) to movement relative to the disk 3 parallel to thewire l2, shaft [8, theactuation of. which willbe herein.- after described. The slide 5 carries four vertical: wires I9, 20, 2| and 22 extending across the disk 3. The wire [9 is nearest to the center of the disk 3. and is designated: by the graduation 0.- The. other wires-20, 21Land Here-designated. 500, .1000 .and 1500 yards.- respectively,

(t), is the period gt time bettween th instant of firing of the projectile and the instant of its intercepting the target. The' the correction in eleva- 3 by the.

3 and carries a stiff: wire. disk 3: parallel to the This wire.

by means of: gears I andinaccords'.

I scale it will be ance with the distance represented by their displacement from the zero, wire. {9.

I A s the range and height scales and the spaciiig of the vertical Wires are all made to the same seen that when the range scale 6, height wire I2 and one of the change of range wires I9, 20,, 2| or 22 intersect a right angle triangle is formed of which th sides represent height and horizontal range respectively, and the hypothenuse represents the direct range (R), while the angle of the hypothenuse or disk 3 represents the elevation angle of the target.

The target speed (St) is set into the mechanism by handle 23, shaft 24 and shaft 25 which carries the dial 26 for indicating the speed set into the mechanism. The speed dial 26 is cylindrical and has three other cylindrical dials 21, 28 and 29 mounted adjacent to. it for rotation by shaft 25.

These four dials are shown in greater detail in Fig. 3 from which their operation and purpose will be more readily understood.

On the outer surface or dial 26 is engraved a scale graduated in miles per hour of the speed of the target. On the outer surfaces of dials 2T, 28 and 29 are engraved scales graduated in secends of: time and representing the time required for the target to move respectively five hundred yards, one thousand yards; and fifteen hundred yards at the corresponding speeds as graduated on dial 26. Above the rings and on a-supporting structure 30 are engraved letters or numbers for identifying the graduations 0n the dials and also index marks 3-! and 32- by which the distance traveled by the target during different values of the preparation periods 31) for various values oft-he speed; of -the target ('St). In the setting disclosed in Fig. 3 it is shown: that: for a speedof the target of two hundred and'five. miles per hour, the distance traveled-by the target; during values of X of five, ten, and'fifteen, secends, is 500, i000 and 1500 yards respectively;

Assuming the Operator knows that ten seconds as the preparation period of time is sufiicient but. that five seconds wouldbe too short a time, hev therefore sees from the group of dials, especially ring 28; that the run of, the target during this, preparation period of ten'seconds is 1000 yards. As this 1000 yards represents the preparation period (X) times the target speed (St) or the distance A-B of Fig. 1', it will beseen that for these particular conditions the distance, AB or RH, minus EH3- is equal to X-St, or 1000 yards.

In setting the ring 26 to the target speed (St) the operator also sets, the target speed; in this case, two hundred and five miles an hour, into the multiplier 33' by shaft 24. The value of ,the period of the timeof flight (t), the generation, of which will be described hereinafter, is alsoset. into multiplier 33 by shaft 34. The output shaft. 35 of multiplier 33 is connectedtmactuate one member of difierential' 36. and is positioned by, the multiplier, in, proportion to t-St or the. distance 13-0 of, Fig. 1, which equals the horizontal range (RI-I3) minus horizontalrange (RI-12).,

Having, determined, from the indicationaboye the dials 21, 28,011 2,9, the distance the targetwill, travel during the selected preparatiorrtime (X), the operator sets in the observedielevation value. (Al) by. turning the handle 9 to rotatethe disk 3= until the index l is opposite the desired value of theseale 8. Forthe assumed,conditions-indi e ed b F iandw nsec nds preparationpe-a riod; the; operator then: moves the horizontal. ranger slide 5.: from the position where its:zero. yard-r. wire l9 :passes .through the: center of disk, 3

may be determined,

responding to the observed range (R) and since the zero wire I9 is permanently spaced from the.

wire 2| a distance representing 1000v yards, the distance of the zero wire from the center of the disk 3 will represent the horizontal range. (EH3);

This relation will be seen from Equation 2 since X-st equals 1000 yards. The rotative positionof shaft l8 connected to slide will therefore also represent the horizontal range (EH3); Since the rotational position of shaft 18 due to the com bined effect of shafts 35 and 38 represents the horizontal range (RH3) and shaft 35 represents (t-St) it Will be seen from Equation 5 that because of the differential 36 the rotational position required of shaft 38 will represent the horizontal range (RHZ) to the point ofintercept-(C').

The corresponding value of height (H) for the assumed conditions is obtained by turning shaft l5 by handle [4 until wire l2 intersects the 1000 yard wire 2| where wire 2| crosses the range scale 6 at the observed direct range graduatio ,4 e

The value of the period of the time of flight is generated by a conventional three-dimensionalcam 39 which consists of a solid rotated'by the shaft 38, the surfaces of the variouslateral crosssections of the solid along its axis forming indi-.

vidual cam surfaces to ive to cam follower 30 and its associated arm an angular motionabout a threaded carriage 40a proportional to the time of flight of the projectile for the range represented by the rotational position of the solid and the value of height represented by the axial position of the follower 40. The threaded carriage 40a for cam follower 40 is moved parallel to the axis of the solid cam to engage the follower Hl wit'h the various lateral sections of the cam, in accordance with the value of height (H), by the rotational position of the threaded portion of shaft l5 which carries the threaded carriage. It will be understood that the threaded carriage is held against rotational movement by guide means not shown. Cam follower 40 is kept in engagement with the cam surface by' spring 4| and its motion is transmitted to elongated gear 42 on shaft 34 by toothed sector 43. The elevation angle of the target at, point C is obtained by a conventional vector-solver 44 the component inputs of which are connected to shaft I5 the movement of which represents height (H) and shaft 38 the movement of which represents horizontal range (RHZ). The output of vector solver 44 is shaft 45 the rotational posi-' tion of which represents the elevation angle (A2) to the point C as shown by Equation 6.

The elevation angle (A3) of the target at point B is obtained from vector analyzer 2. It has been explained that the position of theslide 5 and the zero wire I!) represent the horizontal range (EH3) to the point B. If the operator now rotates disk 3 by handle 9 until the range scale 6 crosses the zero wire [9 where wire l9 intersects the height wire l2 the position of disk 3 and the rotational position of shaft ID will represent the elevation angle (A3) as shown by Equation 3. This position of therange scale 6 is indicated by the dotted line 46 on Fig. 2. l

: The values of elevation angles (A3) as :repre-.

sented by 'theirotational DOSitiOh-OfIShaft' l0, and:

of (A2) as represented bytherotational position of shaft45, are :combined in differential i4'l 1th'et output. of which, shaft 48, represents the elevaa. tionlpredictioniangle (Ut)1which isflequalftox A2+ A-3,"a,s shown-'by Equation 7. e e.

The super" elevation angle' (e). which is; added to the'elevation prediction angleiUtto 'obtain the sight'S'angIe (Us),'as shownfbyfEquationi8 sis-1a: function 30f the height (H) "and the-horizontal. range- (RHZ') when: the 'targ'et' is at:pioihtrsCJ; From experimental data a ballistic three-.dimene... sional cam 49 may be made similar in construe-i.

tion and operation to cam 39 previously described, except that the surface of the solid 'cam is such that cam followerv 50 is moved about its threaded. carriage $5011 on the shaft l5 so that. the-sector 5| rotates elongated gear 52'mountedonxshaft: 53 in proportion to'the'super elevation (e) r '1:

As the sight angle; (Us) is equal to the-pres, diction Tangle (Ut) plu the super-elevation' twr shafts 48. and 53 are connected to differential- 54, the output of which is: gear 55. The-rota-y tional position of gear 55. thereforerepresents. the sightangle (Us). Gear 55 is connected to. shaft :56 through a yieldable drive 51, such*asax centralizing spring. Shaft 56 is connected gto; graduated dial 58. by: gear 59. Corrections may 'As is 1 well known, "the deflection of the sight I due to drift isrproportionalnto the super elevaei' tion, therefore shaft 53 is connected to rotatea deflection dial 65 through a yieldableydrive 66;; shaft 61and gears 68. Corrections may beape plied to the readings of dial 65 by ring dial 6!) mounted'coaxially with dial 65 andtmovedby. gears 10 turned by handle-1|. a

As the time of fuse setting isproportional to the time of flightof the projectile, .the values-of f fuse settings are made visually available by: con;-, necting shaft;34* to. dial 1 2 through a yieldable, drive 13 and shaft 14, Corrections may be ap plied 'to the readings of dial 12 by ring dial 15 mounted ooaxially with dial l2 and moved by gears 16 which is turned .by handle a The yieldable drives 51, 66 and 13 are provided in the connections to the outputdials 58, 65 and 12 respectively, to permit the dials tob locked in position as soon as a-solution has been obtained so' that while the readings are being taken from the dials the operator may change themput settings in accordance withnew observations.

To lock the dials when desired, the ends of; the "yieldable drive connected to the dials are each provided'with a brake drum 18. Cooperating with each. brake drum [8 is a brake-shoe 19 mounted on an. arm 80. The arms are pivoted to the frame of theinstrument on pivots;

8|. The free ends of the arms 80 are adjacent to collars '82 on a locking rod 83 which is actuatedby a .push knob or button 84. The locking rod is normally held in its out position by a spring one. end 'of which abuts against the under sideof button 84 and the other end against the frame of the instrument. 7 e Normally the locking button is in its outpost-z tion and the dials 58, 65and12 are driven in; accordance with the driving'end of the yieldable:

gnu-c3544;

drive Whemthezbuttnn 84 is pressedthetbrakei- 8110652192 come. in: contact with the brake drums" 1'8? andf lock. the dials whilethe. mechanism may be: reset. with: consequent. displacement. of the yieldablel drive. When; the button 8 1 is released: the brakes are releasedami the; dials? come' into. agreement with the new: computed: values.

It is: obvious. that. various changes be. made hy'th'ose skilled in the artinlthes detailsioi. the: invention as disclosedi the drawings: and described: above: withinthe principle andiscopemf' the: invention as. expressed: the: appended. claims;

liclaim z 1;. Apparatusfor use in aiming: aagunicr firing. avprcjectile at? atargetapproaching at a. constant. heightiabove' a horizontaliplane; comprisihgsaiveca ton analyzer including a vector member having: a range. scaleiangularlysettable in accordance with: elevation: angles. of thetargetand also including a first-- component 'slidesettable to positions in' accordance withthe observe'di height; of the: tar-- getandza. second component. slidesettahleztmposttions-in' accordance with the; horizontalz range: of the target, the first slide having amindicating Wire thereon extending from the slide in:v ar.di:- recti'on at right angles to the movement: thereof. and the-second slide having thereon azerozrefer ence=-wire and aplurality of; wiresspaced; at. dise tances therefrom representing predetermined; in crements of. horizontal range through. which thetarget movesduring corresponding preparation. periods oftime and extending from the;s1ide" at right angles to the movement "thereofllmeansiset rememaccordance with theispeed of the=target; means movable in accordance with a computed timeof flight of the projectile, amultiplier settable by'the target speed setta'ble'means and the; time offlight movable means, means for setting the second slide with that. one of it movement. wires corresponding to-the distance traversedtin= a preparation period in. at position. corresponding: with the observed slant range and elevation: of: the target including anoperatingqshaft' and aldifzferential one side of which is connected; to the output-of the multiplier: and the other. two. sides; of which are connectedto' the shaftandi thezseczond'slide respectively, ballistic: computing means-- connected to the first slide and. toltliei operating: shaft of the second slide settingmeansfas inputs and having an output movediniaccordanceg'witlr the time of flight, and motion transmittingzmeans connecting the output ofth'e ballisti'cdcomputing means and the'timeof flight movablecmeans.

2i" Apparatus for use in-aiming axgunzfor'firs ing a projectile at a=-target approachingtataaacom stant height above a horizontal: plane; comprising a vector analyzer including-at vector member having a range scale angularly. ettahleeiniaccorm ance withelevationangles of the target: and also includinga first componentslide .settable;to.-posi-, tions=in accordance with the observed. height; of" the target and a secondcomponent:slidezsettableg topositions inaccordance with the: horizontal; range of the target, the first :slide; having an; in;- Y dicating wire thereon extendingzfromi the. slide:- in a' direction at right angles to the. movement thereof and the second .slidewhaving *th'ereoira'v zero.- reference wire. and aplurality ofl wiresspaceda at distances therefrom. representing: predetermined: increments of horizontal; range. through which the target moves during corresponding: preparation-periods of. tiine and extendingrfrom the slide at'right angles to the mcvementthereofi.

the target; meansmovable in accordance with a. computed time of flight. of the projectile, a multiplien settableiby the-target speed settable means and time of:flightmovablemeans;mean for setting the secondslide with thatoneofiits increment wires corresponding to' the: distance traversed. in: a. preparation. period: in a position: correspending with the observed slant rangezand: elevation of! the target. including anloperatingshaft. and; at diirerential oneasidezofwhich is connected; to* the" output of the'multiplier and the other two sides of which are connected to:the;shaft and. the second? slide: respectively; ballistic computing means conne'cteditozth'e first slide and-:toi the operating: shaft. of theisecondslide' setting means as. inputs; and having an: output moved" in accordance witltthe time of; flight; motion transmitting means connecting the output ofth'e ballisti'czcomputin'g: means and the time of flight movable meansiand means connected to the target speed settable means forsindicating:increments of movement. of the target: for corresponding periods: of: preparationatimez 3; Apparatus .forusein aiming. a gun for firing aprojectile. at a target approaching. at a constant height above a horizontal plane;. comprising a. vector analyzer including a vector member hawinga rangescalei angularlysettable in accordance: with elevation angles of the target and also including a first componentslidesettable' to positions' in accordance With the observed heightiof the target and asec'ond component slidesettableto positions in accordance with the horizontal range of thetarget, the first slide having an in-" dicat-ingwire thereon extending from the'slide in adirection at right angle to the movement thereof and the second slide having thereon a zero reference'wire'and'a plurality of wires spaced at distances therefromrepresenting predeter-- mined increments of horizontal range through which" the target moves' during corresponding preparation periods of" time and extendingfrom the slide at rightangles'tothe movementthereof, means settable in accordance with the speed of the target, means movalole'in accordance withia computed time of flight of the projectile; a multiplier, settahle by the targetspeed settablemeans and thetime offlight movable means, means for setting the second slide with that one of its increment wires corresponding. to the. distance traversed in a. preparationperiodin a position corresponding to the-observed. slant range and elevation. of. the. target, including, an operating shaft P and adiff'erential onesideofwhich is-connected.

totheoutputof the'multiplier. and the other. two. sidesofwhich are connectedto the shaft and the second slide respectively, ballistic. computing. means connected; to. the. first-slide and-to the operatingishaft of. the; second slide setting means as inputs and. having, a first output movedin. ac cordance with the :time offlight and asecond out-- put moved in accordance with the super elevation angle, motiontransmitting mean connecting the firstvoutput: of the. ballisticrcomputing, means and the movable-timeofiflight means, a .vectorsolver settable :by; the-first: slide and the operating shaft of the second slide'settingimeansi means responsive-to angulanmovement of the rangescale-from an initialpositionmepresenting an observed? posi-- tionof,- the, targetto aposition? intersecting both: the first. slide-wireand the zero reference 1 wire of the'second slide; means for-combiningthe'moveiment of they responsive means and-thetoutput of meansa'settable in accordan'cm withzthesspeedz Ofs: the} vector solvenyand meansfor; combiningi'the output of the last mentioned combining means and the second output of the ballistic computing means whereby the sight angle is obtained.

4. In apparatus for use in the aiming of guns, a vector analyzer settable to represent the position of a target, means for initially setting said vector analyzer in accordance with the observed angular relation of a target from an observing station, a pair of rectangular component members associated with the said vector analyzer one of said members having a single indicating wire for indicating the height of the target from the observing station and the second of the said members having a plurality of indicating wires spaced to represent increments of movement of the target, means for setting the height component member in accordance with the height of a target, means for setting the second component member to bring the wires selectively into agreement with the horizontal range corresponding to the setting of the said vector analyzer, said last mentioned setting means including means settable in accordance with a horizontal range value and the output of a multiplying mechanism having two input members, means for actuating one of said input members in accordance with the target speed including target speed indicating means, means for actuating the other of the said input members in accordance with the time of flight of the projectile, a vector solver having one component input directly actuated by the means settable in accordance with a horizontal range value and a second component input actuated by the means for setting the height component member and having a vector member angularly positioned in accordance with the setting of the said component inputs, means associated with the target speed indicating means for indicating the time required by the target to traverse the increments of movement of the target represented by the indicating means associated with the second of said pair of component members, and means for combining the resulting angular positions of the vector member with the means for angularly setting the first mentioned vector analyzer, whereby the output of the combining means represents the angular movement of the target during the time of flight when the first mentioned vector analyzer is set in accordance with the intersection of the height component wire and a second of the plurality of indicating wires representing a desired increment of movement of the target from the observed position.

5. In apparatus for use in the aiming of guns, I

a vector analyzer settable to represent the position of a target, means for initially setting said vector analyzer in accordance with the observed angular relation of a target from an observing station, a pair of rectangular component members associated with the said vector analyzer one of said members having a single indicating wire for indicating the height of the target from the observing station and the second of the said members having a plurality of indicating wires spaced to represent increments of movement of the target, means for setting the height component member in accordance with the height of a target, means for setting the second component member to bring the wires selectively into agreement with the horizontal range corresponding to the setting of the said vector analyzer, said last mentioned setting means including means settable in accordance with a horizontal range value and the output of a multiplying mechanism havingtwo input members, means for actuatingone of said input members in accordance with the target speed including target speed indi-' cating means, means for actuating the other of the said input members in accordance with the time of flight of the projectile, a vector solver having one component input directly actuated by the means settable in accordance with a horizontal range value and a second component input actuated by the means for setting the height component member and having a vector member angularly positioned in accordance with the setting of the said component inputs, means associated with the target speed indicating means for indicating the time required by the target to traverse the increments of movement of the target represented by the indicating means associated with the second of said pair of component members, means for combining the resulting angular positions of the vector member with the means for angularly setting the first mentioned vector analyzer, and ballistic computing means todetermine' the time of flight of the projectile,

said computing means having input elements 7 connected to the means for setting the height component member and the means settable in accordance with a horizontal range value.

6. In apparatus for use in the aiming of guns, a vector analyzer settable to represent the position of a target, means for initially setting said vector analyzer in accordance with the observed angular relation of a target from an observing station, a pair of rectangular component members associated with the said vector analyzer one of said members having a single indicating wire for indicating the height of the target from the observing station and the second of the said members having a plurality of indicating Wires spaced to represent increments of movement of the target, means for setting the height component member in accordance with the height of a target, means for setting the second component member to bring the wires selectively into agreement with the horizontal range corresponding to the setting of the said vector analyzer, said last mentioned setting means including means settable in accordance with a horizontal range value and the output of a multiplying mechanism having two input members, means for actuating one of said input members in accordance with the target speed including target speed indicating means, ballistic computing means controlled jointly by the means settable in accordance with a horizontal range value and the means for setting the height component for actuating the other of the said input members in accordance with the time of flight of the projectile, and means connected withthe target speed indicating means for indicating the times required for the target to traverse the several increments of movement of the target represented by the spacing of the plurality of indicating wires associated with the second of said pair of component members, thereby enabling the operator to select the proper indicating wire to denote the horizontal range of the target at the observed position set into the vector analyzer so that the position of the target after a predetermined increment of movement will be indicated by the intersection of a second indicating wire with the height wire.

WILLIAM H. NEWELL, 

